[vecher]

Not sure where this should go.. Please move if its not in the right place

Question about a 50L6 tube.. I have 5 tubes that all check bad for shorts.. Is this normal ? Does this tube have high leakage? I cannot seem to believe all the tubes are shorted.. Or is this a common problem...

Thanks
Skip..

[morzh]

I forgot but in one of Kirk's radios where I had a 42 tube in the output I had the 42 that had a filament short (and was working). I bought another one and it was shorted too. And then another (the short disappeared after a while....????) Eventually I got one that was not shorted.

I do not think it could be normal for a tube to show a short. Even if it works (which is quite possible depending on the arrangement).

[TV MAN]

Maybe your tube tester? What tester(s) do you have? My Hickok did something weird like that on a 6SN7GT recently, even with the tube out of the socket... haven't gotten into it yet..

[morzh]

Possible....though a similar suggestion was expressed to me back then and no, it was not the tester.

[vecher]

Ok I used a Hickok 600A tester and a Heathkit IT-17.. All showed short on 5 tubes.. Doesn't seem right. But maybe all 5 are bad? I wouldn't think so But who knows..

Going to see if I have any 25L6 or similar to see what they read..

Skip..

[morzh]

I think all 5 are bad.
This said, you might be able to use some of them in some circuits. It depends on how they are powered.

[vecher]

Ok plugged one of the tubes into radio the Zenith 5D011. All is well plays good with load and clear volume... No excessive current draw 117 Volts at .25 amps...

Thanks
all for the help..

Skip...

[klondike98]

I'm curious. If there is a short in the tube, does that mean that there is an unwanted connection between elements inside the tube? For example, between a grid and the plate. If so, shouldn't you be able to detect a short by putting your ohm meter across the various pin combinations? Or is there something else that can cause tube shorts?

[vecher]

I tried that. The tube I am using I checked for shorts pin to pin Tube cold. No shorts.. But when put in Tester showed short I think between Cathode and Filament according to the chart with my Hickok 600A..

Tube works in radio No problems..

Skip...

[morzh]

The short is mostly between the filament and the cathode, and this could be benign in some arrangements. In some others you might have hum. If it works, you are fine.

[Jayce]

It can be amazing how you sometimes find faulty tubes in groups. Usually that doesn't happen, so it can throw one off when it occurs and it can be easy to blame the tube checker. One reason why my friend always said to keep a couple testers around. I have had a similar issue with type 47 tubes lately. I've managed to get three radios with push-pull 47s now and in all three cases one 47 in each radio was burnt out or would burn out as I was testing it. Tapping the tubes lightly would cause an arc inside them, but nothing else. I actually watched one burn the filament out on my tester when I tested the tubes in my Philco 90X.

[Kenneth F. Besso Jr.]

THAT is what ,,I was show,,was to flick your finger against the tube ,,in tester,,while pushing the test button,,for any kind of short,,be-side the short test,,,CHEERS

[David]

50l6, 50C5, 35W4, 35Z5, If working on a All American set (AC DC) that has a bad tube good chance one of the following.  David

[Paul Philco322]

Outputs and rectifiers often are candidates to go, if they were pulls maybe they are all bad, really.

Paul

[rocketeer]

I have 7 50L6GT here and none test as a short.